Active Infrared Thermography (IRT) is an outstanding technology for the rapid detection of near-surface defects (like, e.g., cracks or delaminations) in metals and composite components.

Compared to ultrasonic methods, there are several benefits but also drawbacks. Exactly like Laser-Ultrasonics, Thermography does not need any coupling agent.

The main advantage is the ability to quickly inspect large, relatively flat surfaces over their entire area. However, the penetration depth and spatial resolution are limited compared to LUS.

A major advantage of this method is its existing aviation certification and established international standards.

Two high-powered halogen lamps heat the component’s surface by typically 10°C. A thermal imaging camera records a video of the surface temperature from a distance of approximately 70 cm. The field of view is 40 x 32 cm². Using mathematically complex algorithms, a model of the workpiece is calculated based on the temporal progression of the surface temperature. Deviations from the ideal temperature profile indicate material defects such as holes, cracks, delaminations, air pockets, or moisture. Typically, measurement plus reconstruction last between two and three minutes.

RECENDT is in the process of developing new reconstruction methods to enable detection of smaller faults and faults at greater depths in the future.

Burgholzer, Peter / Gahleitner, Lukas / Mayr, Günther
Linking diffusive fields to virtual waves as their propagative duals
Physical Review Applied 24, 044094, APS Journals, published 29 October, 2025, DOI: 10.1103/8gkn-936j

Burgholzer, Peter / Thummerer, Gregor / Plasser, Holger / Mayr, Günther
Three-Dimensional Thermographic Image Reconstruction Using the Virtual Wave Concept
ASNT Nondestructive Testing Handbook 4: Infrared Testing (IR), fourth edition, Oct. 2024, Chapter 12 (Processing and Modeling for Thermal and Infrared Testing), Part 12, pages 577-578, ASNT (The American Society for Nondestructive Testing)

Burgholzer, P. / Mayr, G. / Thummerer, G. / Haltmeier, M.
Heat diffusion blurs photothermal images with increasing depth
2022-06, Journal of Applied Physics , Vol. 131, No. 211101, DOI: 10.1063/5.0093315

Burgholzer, P.; Thor, M.; Gruber, J. & Mayr, G.
Three-dimensional thermographic imaging using a virtual wave concept
Journal of Applied Physics, 2017, 121, 105102, DOI: 10.1063/1.4978010